Only direct play stereo AC3 when connected to a receiver, fixes #236.
Use scheme attr instead of assuming https for port 443.
Try localAddresses for shared servers, fixes #192.

With multiuser, this is much more important.
Fix local IP usage when remote IP is unavailable.

Our local IP stuff only worked when the remote connection was also available.
Among other things, we need to use the path for the shared sections instead of
the key, since the key has the host included already.
Request sections directly from shared servers, fixes #239.